>Did anybody know, if (and how) it's possible to find out with which>compiler a Windows executable file was compiled.

It is almost certainly possible, but the "how" part that I know is by
looking for idioms in the generated code. I could do this pretty
easily when I worked on compilers for Sparc and looked at a fair
amount of code; someone who has worked on compilers or debuggers for
Pentium could probably do the same.